Oxygen concentrators are used, for example, as a source of high purity oxygen for medical applications. An oxygen concentrator will separate air into two gas streams, one of which consists primarily of oxygen and the other of which consists primarily of nitrogen. A pressure swing molecular sieve oxygen concentrator typically has at least two molecular sieve beds. Each molecular sieve bed typically consists of a closed cylindrical container partially filled with a sieve material, such as zeolite, which will pass a flow of oxygen molecules while blocking the flow of larger nitrogen molecules. In operation, a compressor applies filtered pressurized air through a flow control valve to an inlet port on one of the molecular sieve beds and about 95% pure oxygen flows under pressure from an outlet port on such bed. The oxygen may flow to an accumulator and then pass through a pressure regulator, an optional flow meter and a final filter to a patient. As oxygen flows through the sieve bed, the separated nitrogen is retained in the sieve bed. After a short time, one or more valves are changed to apply the pressurized air to the inlet port of a second sieve bed and to vent the inlet port of the first sieve bed. A small portion of the pressurized oxygen output from the second sieve bed is delivered to the outlet port of the first sieve bed to purge nitrogen and any other trapped gases from the first sieve bed. The valves are periodically reversed to alternate the sieve beds between the gas separating cycle and the trapped gas purging cycle. The optional accumulator holds a volume of concentrated oxygen under pressure to provide a continuous oxygen flow when the valves are cycled.
In prior art oxygen concentrators, the molecular sieve beds are constructed as individual components which typically each includes a cylindrical container. The accumulator is still a third container. A typical oxygen concentrator uses at least two molecular sieve beds which must be connected together and connected to valves either with tubing and fittings or with manifolds. The number of fittings and connections for handling the pressurized air feed gas and the pressurized oxygen outlet gas present a potential for leaks and assembly errors. Further, both the number of parts required and the time required for assembly can adversely affect the reliability and the manufacturing cost of prior art oxygen concentrators.